Underfeed chain-grate stoker



July 7, i925. 1,545,244

R. A. FORESMAN UNDERFEED 01mm GRATE STOKER Filed Oct. 14, 1920 2 sheets-sheet 1 INVENTOR ATTORNEY a citizen of the United States,

of Essin on, in the county of Delawa1e and Patented July 7, 1925.

UNITED STATES ROBERT A. FOBESMAN, F

PATENT rot-m5.

ESSINGTON} PENNSYLVANIA,

ASSIGNOB TQ was-rum HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

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: Application filed October-1,4, 1920. Serial No. 416,963. I

. To whom it'may concern. 1

Be it known that I, ROBERT A. FORESMAN,

and. a residentin one stoker elements whereby the advanwhich shall be adapted tohandle'fuels of.

- of heat energy therefrom,

tages of both the underfeed and of the chain grate types of construction are attained.

A further object is to produce a stoker the greatest amount together with ease of installation and maintenance.

various types to obtain These and other objects attained will be more manifest in the description given in the following specification in which Fig. 1 is a side view, partially in section and partially in elevation of a stoker embodying my invention, Fig. 2 is a plan view and Fig. 3 a detail sectional view on line III-III of the apparatus shown in Fig. 1. I

In my improved stoker device, I provide a chain grate stoker utilizing the underfeed principle, thereby gaining the advantages of each of the above well known types of stokers. The grate is composed of a series of movable sections, alternate sections beingelevated above the adjacent sections, thus forming a trough or retort into which fuel is fed from a hopper by an associated ram, reciprocatingin the forward portion of the trough. In a stoker of this construction, fuel is fed into the retorts from beneath and allowed to bank in the forward portion of the retort where it has ample time to coke, thus permitting the underfeed principle to be fully utilized. The elevated chain section is open throughout its length, thus forming ai-r admitting surfaces corresponding to tuyere sections and the lower chain section, which is covered at its forward portion, constitutes a base portion for the retort. By this construction, I obtain an even distribution of fuel regulated in such a manner that complete combustion is obtained and the ash disposed of without the use of dump grates or auxiliary means. By forming the grate in sections of uniform size, I

readily construct a grate adaptable to any s1z e o f furnace, in accordance with the unlt principle.

Referring to the drawingsfor a more at "taileddescription, I show a hopper at 10,

opening at its lower portion into a trough 11 in which reciprocates-ia plunger- 12, this plunger being operated in any convenient manner. The fuel isfed through the trough 11- over a raised portion 13, from which "it is carried by moving chain grate sections 16 and 19. Plates 15'up'on which rests the upper portion of the elevated chain section 16, form the sides of the stationary portion of the retort and a plate 14: forms the bottom portion thereof.

Power is transmitted to the grate sections through shafts 17 and 18, respectively. The lower chain section 19 travels beneath the bottom plate of the stationary portion 14 of the retort. Air is delivered, under pressure, to, the grate from. air boxes ,20. At the rearward portion, sprocket wheels carrying the chain grate sections revolve about a common shaft 21 and the entire grate structure may be uniformly operated by applying power to the single shaft 21. The stoker as a unit is readily movable on wheels 22 and 23 if for any reason it must be removed from the furnace.

Having thus described the arrangement of a stoker embodying my invention,'the operation thereof is as follows: The shaft 21 is drlven continuously by means, not shown, such for example as a separate electric motor or by connections to the ram-operating device, although it is preferable that the speed of this shaft may be subject to inde. pendent, ready and wide control as determlned by the rate of combustion of the fuel burned in the furnace. When the ram 12 is reciprocated by any suitable means and air supplied to the chamber 20, fuel is forced from the hopper 10 over the plate 14 into the retort situated between the low chain 19 and the two immediately adjacent high chains 16. Air is supplied to the fuel through the high chains 16 and combustion ensues in A For rapidly burning fuels, such ias" having a high gaseous content, the chains" 16 and 19 are operated at relatively high speed so that by the time the fuel'is consumed, the residue has reached the back of the furnace.

If, on the other hand, the fuels have a relatively low gaseous content and are of slow combustion rate, the chains are moved somewhat more slowly in order that unburned fuel shall not be discharged at the rear of the furnace.

I have shown a furnace made up of alternate elevated and depressed chain sections, as shown more clearly in Figs. 2 and 3, but obviously this arrangement may be varied in that two or more depressed chain sections might I e separated by single elevated chain sections or by two or more elevated chain sections, all as dictated .by the size desired for the retorts and for the tuyeres with re spect to the most desirable chain widths to be used.

In this same connection, the extreme adaptability of my furnace construction to fire boxes of different sizes should be pointed out. The various chain belts are of unifmm width and carried on I interchangeable sprocket wheels, these sprocket wheels in turn being mounted on shafts which may be made of any length. .Thus the total grate may be of any desired overall width and this overall width may be portioned off into a greater or less number of retorts as dictated by the specific operating conditions. F urthcrmore, the ratio of the retort width to tuyere width may be readily changed as for the consumption of a radical different type of fuel.

\Vith a given furnace installation, by the independent adjustment of the ram speed, of the belt velocity, and of the air pressure, an extremely wide adjustability is provided, as demanded by different types offuel.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications. without departing from the spirit thereof, and I desire. therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim 1. In a stoker comprising a fuel feeding mechanism, retorts having portions of progressively diminishing depth, said retorts being partially defined by chain grate sections of which certain sections are elevated above the others at one end.

2. A mechanical stoker comprising a plurality of chain grate sections arranged to define the bottom and the upper edges of a retort and an underfeed device communicatin with the retort.

3. i mechanical stoker comprising fuel-- feeding mechanism including a trough and a plurality of chain grate sections defining the bottom and the upper edges of a retort, the trou h extending into the retort for supplying f uel thereto.

4-. A feeding mechanism including a trough, a rctort chain grate section partly underlying thetigough, and tuyere chain grate sections arranged at the sides of the retort chain grate section, and defining therewith the top edges and the bottom of a retort, said trough being arranged to discharge fuel into the retort.

5. A mechanical stoker comprising a fuelfeeding mechanism and series of chain grate sections, certain of said chain grate sections being elevated at their forward ends, others of said chain grate sections being of relatively lower elevation at their forward ends in order to define the top edges and the bot-- toms of retorts, said chain grate sections being at equal elevation at their rear ends.

mechanical stoker comprising fuelforward ends than an intermediate chain gratesectionand the fuel-feeding mechanism being arranged to deliver fuel between said elevated chain grate sections.

7. An underfeed stoker comprising a hopper, a trough communicating withthe hopper, a fuel-feeding mechanism associated therewith, a grate composed of movable chain grate sections of different lengths and of different elevations at their forward ends to define the bottoms and the top edges of retorts, the longer chain grate sections being at the higher elevation, and a stationary guide member overhanging the forward portion of the shorter chain grate section and connected to the trough.

81 In a mechanical stoker, fuel-feeding mechanism, movable chain grate sections, adjacent sections being of different elevation at their forward ends and of equal elevation at the rearward ends so as to define the bottoms and the topedges of retorts, and an air supply chamber located beneath the chain grate sections to supply air thereto.

9. An underfeed stoker comprising fuelfeeding mechanism and movable chain grate sections, certain of the sections being elevated above the others'to form upper and bottom portions of fuel-receiving retorts- 10. An underfeed stoker, comprising fuelfeeding mechanism and movable chain grate sections arranged to form 'portions of retorts, alternate chain grate sections being elevated above the adjacent chain grate sections, the elevated chain grate sections forming the tuyeres and the depressed chain grate sections forming at least in part the bottoms of the retorts.

11. In an underfeed a series of chain grate sections other of said chain grate sections ing over the forward portions of the depressed chain grate sections to form stationary bottom ortions for the retorts.

13. An under nately disposed tu ere sections and retort sections, said tuyere sections embodying endless chain units, and said retort sections eed stoker comprising alterembodying endless chain units at a lower elevation than said tuyere chain units.

In testimony whereof, I have hereunto subscribed my name this eleventh day of October, 1920. a I

R. A. FORESMAN. 

